hoffmann



No. 624,489; Pa tented May 9, I899. E. a. HOFFMANN.

STOP MECHANISM.

(Application filed Mar. 5, 1898.) (No Model.) 2 Sheets- Sheet nms PETERS co. Pno'rouwa. wAsulNsmn. n. c.

No. 624,489. Patented May 9, !899. E. G. HOFFMANN. STOP MECHANISM.

(Application filed Mar. 5, 1898.)

2 Sheets-Sheet 2.

(No Model.)

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UNTTED STATES PATENT OFFICE.

ERNST GUSTAV I-IOFFMANN, OF LONDON, ENGLAND.

STOP MECHANISM.

SPECIFICATION forming part of Letters Patent No. 624,489, dated May 9, 1899.

Application filed March 5, 1898.

To (1, whom it ntay concern:

Be it known that I, ERNST GUSTAV HOFF- MANN, a subject of the German Emperor, residing at London, England, have invented a certain new and useful Improvementin Stop Mechanisms for Turning-Machines, of which the following is a specification.

In operating certain machines or apparatus, such as lathes or machines having cutters which are presented to rotating bodies, it is sometimes desirable to provide means whereby the machine may be stopped immediately should anything interfere with the proper operation of the cutters or the like. In order to provide for this contingency, a stop mechanism of some kind is desirable; and the present invention consists of an arrangement of this kind which has been specially designed for use with an automatic machine for cutting balls or the like from a rotating wire by means of a reciprocating cutter. The invention, however, is applicable to machines of a similar nature, in which it is necessary to provide an automatic stop for a reciprocating part.

The stop mechanism according to the present invention consists of a species of springbnffer connecting the cutter-slide through a suitable arm with the operating mechanism, which may be a lever worked by a cam, the buffer being interposed in such a way that the slide is not driven positively, but only through the pressure on the spring in the buffer device, so that the action of the device relies entirely upon theyieldin g of the spring.

One form of my invention is illustrated in the accompanying drawings, in which- Figure 1 is an elevation showing a general view of the mechanism operating a slide carrying a circular cutter. Fig. 2 is a plan of the spring-buffer and stop device, partly in section. Fig. 3 is a similar View with the parts in another position. Fig. 4 is a side sectional elevation of the spring-buffer on line y 3 Fig. 2; and Fig. 5 is a cross-section of Fig. 4 on line z z of same and looking to the left, the central part or connecting-rod being in elevation and the stop device being shown in addition also in elevation. Fig. 6

is a front elevation on a reduced scale, showing a portion of the frame of a machine, such as a turning-machine, to illustrate the arrangement by which my invention is caused Serial No. 672,752. (No model.)

to operate a stop mechanism, which in this case is a belt-shifter. Fig. 7 is a sectional plan on line 1 1, Fig. 6. Fig. 8 is a detached view, on an enlarged scale, of a portion of the belt-shipping shaft, the view being partly a section on line 2 2 of Fig. 7. Fig. 9isasimilar view showing the parts in another position, and Fig. 10 is a cross-section of Fig. 9 on a line 3 3.

The mechanism is shown in the drawings adapted to the automatic ball making machine previously referred to and from same its adaptation to other devices will be readily understood. In the operation of this machine it was of importance to provide means where+ by the machine would be stopped immediately should anything interfere with the proper cutting of the knives or should the wire be at an end. In order to make such mechanism practical and positive, the stop mechanism is so arranged that the action of the cutter itself reacts upon the same directly. The adaptation of this stop mechanism to the machine in question also had in view the possibility of making the machine stop when the balls increased in diameter by a very small amount, which increase is possible when the cutters have become dull.

a is a pivoted leverwhich drives the slide a, upon which the cutter a is mounted.

b is the connecting-rod, which transmits motion from'the cam I) through a crank B to the cutter-slide, and between a and b the stop mechanism is interposed.

b is a spring to withdraw the connectingrod 1).

c is a housing containing a springs, against which the connecting-rod presses, a reduced end b of said rod acting to guide both rod and spring. l

d d are projections forming journals upon 0 for the purpose of mounting it movably in lever a.

m is a cap on the housing, and n a lock-nut.

Bushings e e fit upon the projections'd d and form bearings within which the housing 0 swivels. This construction of bushings c has been adapted merely to provide means for the quick removal of the stop-motion from lever a. It will be noticed that thelower end of lever a has a yoke the ends of which are slotted, so that as soon as bushings e are fon either side.

withdrawn sidewardly the journals d d and housing a can drop out of the lower end of lever 01, passing through the said slots. Said bushings e e are held in position by a screw (See Fig. 1.) In line with the axis of the journals (1 d a hole is formed in which is a rod g, capable of moving freely longitudinally, said rod galso passingthrough pin h passes through the connecting-rod b said connecting-rod is provided with a slot 70, which in this case answers the purpose of a cam, while a slot is also formed in the housingc to allow the pin to move therein. As soon as the spring 0 is compressed, which will happen when the lever a is prevented from moving to the left in consequence of the cutter-slide being hindered in its forward movement, the cam-slot will force small pin h and with it the rod 9 cndwise, as shown in Fig. 2.

The pin it is fastened into a brass cap Z, which is provided to prevent any oil or chips from the machine dropping into the interior of the stop mechanism, such cap covering the slot in the housing 0: The n ut m is provided for adjusting the pressure of spring 0, and n is a lock-nut. The stop device consists of a lever 0, having a T-head 0 and mounted upon shaft '19 and capable of rocking same and acts in connection with -rod 9 in the following manner: In Fig. 2 the stop mechanism is shown when the cutter-slide has ceased its forward movement, because it has reached its full stop; but the cam I) still imparts motion to said connecting-rod, which in turn compresses the spring 0. It should be understood that in the construction shown the spring 0 yields by being compressed at each revolution of the cam by reason of a lump b which is formed on said cam and the purpose of which will be hereinafter explained. Such compression of spring 0 permits connecting-rod b to be further pushed into the housing 0, and therefore causes the cam-slot 7a to effect a sidewise movement of rod g through the medium of pin h.

One end of rod g, protruding beyond its hole, acts upon levero under certaincircumstances. \Vhen the cutters properly perform their work, the outward movement of rod 9, Fig. 2, only takes place after it has passed head 0 of lever 0; but should the free forward movement of the cutter be-interferred -with, and therefore the spring 0 meeting with which permits the belt to go on the loose pulley or to open a friction-clutch on the machine, as the case may be. In either case the machine will be immediately stopped.

In its normal position the rod 9 will hardly protrude at all beyond the journal end, and therefore it will pass clear of same. In such normal position the rod 9 has a further ob- I ject, namely-to prevent the connecting-rod I) being pushed too far outward by spring 0', because such rod gwill come in contact with the end of slot j in 'rod 1), which provided for a limited movement of said pin g within said rod. Fig. 3 shows the position when rod' g is not protruding and is passing head 0, as is the case during the ordinary cutting opera tions.

It will be seen that any interference with the normal forward motion of the cutter is bound to react upon spring 0, which cannot stand the increased resistance, and therefore no matter what the relative position of the stop mechanism as regards head 0 of levero may be it is bound to act upon said lever by means of rod 9, unless, indeed, the whole mechanism has been moving to the left as far as is necessary to permit rod 9 to clear the edge of head 0, in which case only lever 0 will not act upon the belt-shifter or the like, and therefore the machine will be kept going.

The small pin it can be withdrawn instantly by means of cap Z, and therefore rod 9 can also be withdrawn instantly by means of its knurled end 9', and hence these delicate parts can be subjected to examination and repaired in a-few moments without requiring the taking apart of other parts of the machine.

It need hardly be mentioned that rod- 9 where it strikes head 0 is hardened, as is also the striking-surface of the head 0. As soon as the return movement of the parts sets in the first action of the connecting rod 1) going backward will be to move rod 9 inward until it has reached a position to clear head 0, and only then will all the parts move backward together as if they were one solid piece.

The lever 0 can of course be adjusted upon its shaft 19 in such a manner that it will be very sensitive, and, together with the fact that lever on transmits motion and power to the cutter-slide, which it drives in proportion of, say, about one to four, it followsthat the retardation of the cutter by only on e-thousandth part of an inch will multiply to the-four-thousandths part of an inch at rod g or in similar proportion, according to the relative lengths of lever a.

By the foregoing it will be clear, therefore, that should the cutter, for instance, strike the wire or the like from which the articles are being formed when the latter does not revolve in consequence of its having run so short that its clutch or holding device cannot hold it any longer, the cutter will be prevented from penetrating into the wire, and therefore causes spring a to yield, which yielding sets in motion rod g and lever 0, which latter acts upon the belt-shifter, which shifts the belt it has difficulty in entering the wire and that the spring does not sufiice to take care of the increased resistance, it will therefore yield with the same resultnamely, the rod g will be set in motion-forcing away lever 0, which latter causes the machine to stop.

4 If necessary, lever may be provided with a micrometer adjustment, so as to make it must yield,with the result that rod g is pushedout and ,connectinglever 0, stops the machine.

If the functions of allthe parts on the drawings are followed, it will be clearly seen that the spring 0 must be compressed a considerable amount before the rod 9 has been pushed sidewise by the movement of the connectingrod 1) sufficiently to effect the movement of head '0, which either shifts the belt on the loose pulley or opens the friction-clutch. Assuming that the cam b were plain and without the lump b and that the cutter meets with an obstacle preventing it normally penetrating the wire or stock at a point when the cam Z) has traveled about half of its circumference, there would be sufficient stroke on the cam left to compress the spring in the coupling sufficiently for the purpose of the stop mechanism to act. To make this quite clear, we will assume that the cam circumference equals a spiral of one-half of an inch per revolution. Now in the event of half a revolution having already taken place there would be one-fourth of an inch stroke still left, which would be more than sufficient to compress the mainspring in the coupling to such an extent as to cause the stop mechanism to act. Assuming, however, that threefourths of an inch of the circumference of the cam has traveled before the cutter meets with its obstruction, which prevents it further penetrating into the wire, then only one-eighth of an inch would be left in the form of stroke of the circumference of the cam, which might or might not just be able to effect the acting of the stop mechanism. Any less portion of one-fourth of an inch of the circumference of the cam would, however, not cause the stop mechanism to act, simply because there would not be sufficient stroke left to move the connecting-rod b, and indirectly the rod g, suff1- ciently to effect the stoppage. The parts would be moved almost to the stopping-point but as soon as the power ceased and the movements were reversed all the parts would resume original position.

If we now consider the functions of the cam 19' as shown and provided with the lump b it will be seen that, assuming the cutter does meet with the obstruction while the cam has actually traveled the entire length of its circumference except that portion occupied by the lump, and just at that point the cutter still meets with an obstruction which prevents it from going right home to its normal limit, such obstruction, encountered even as late as that, will cause the machine to stop, because the lump left on the highest pointof the cam is of sufficient height to compress the spring 0 far enough and therefore to move the rod g endwise asufficient amount to effect the stoppage. The obstructions the cutter can meet are numerous. Among the most common are dullness of cutter, requiring more pressure than the spring 0' is set for or momentary insufficiency of the oil-supply, causing the cutter to penetrate the wire with greater difficulty, or hard spots in the wire. This point of the position of the machine at which such obstruction may occur, it will be understood, may readily be a point on the,

a fixed collar H and a spring I between same and the frame,which spring is in compression and tends to force the shaft E to the left hand. The shaft E is cut away, as at J, Figs.

8, 9, and 10, and in the gap so formed is left a shoulder K. The rock-shaft p is supported in the frame in a sleeve L, forming a bearing, and carries at its end a disk M, having a pin or projection N, the edge or face of such projection forming a shoulder adapted to engage with the shoulderK of shaft E; When the machine is operating, the shaft is forced back against the spring I and is held by the projection N, as shown in Fig. 8; but as soon as the shaft 19 is rocked the projection is removed and the shaft E is forced forward into the position shown in the other figures, and the shipper F brings the belt onto the loose pulley. If the weight of. the lever o is not sufficient to keep the shaft p in position to normally hold the'projection N against the shoulder K, a spring T, secured to the lever 0 and'to the frame D, may be employed.

What I claim is- 1. In combination, a connecting-rod,means for reciprocating the same, a lever rocked by said rod, a part operated thereby, and a spring interposed between said rod and lover through which the power is transmitted, said spring being continuously altered in length during normal working of the parts but only sufficiently under abnormal working, to efieot a stoppage of the machine, substantially as described.

2. In combination, aconnecting-rod, means for reciprocating same, a tool operated there-' by, a part slidable by the connecting-rod adapted to be moved by the latter, a spring interposed between the rod and the tool, and a stop mechanism adapted to be operated by the slidable part on the alteration in length of the spring caused by abnormal conditions of Working, substantially as described.

3. In combination, aconnecting-rod, means for reciprocating same, a tool operated thereby, a part slidable in the rod adapted to be moved by the latter, a spring interposed between the rod and tool, a stop mechanism, a pivoted lever'connected to same, and a T- head to the lever presenting a considerable surface for the slidable part to act on, upon alteration in length of the spring caused by abnormal conditions of working,substantially as described.

4:. The combination with a connecting-rod forming part of a tool-operating device, and a lever forming part of a stop mechanism, of a housing for the end of the rod, a spring compressible by said rod in said housing, a rod slidable in said connecting-rod at right angles thereto, and passing through the housing, a cam-slot in said connecting-rod, and a pin projecting from said slidable rod into said slot, so that a movement of the connectin g-rod in the housing caused by compression of the spring, will move the slidable rod at right angles to the connecting-rod and cause it to strike the lever forming part of the stop mechanism, substantially as described.

In testimony whereof I have hereunto set my hand'in the presence of two subscribing witnesses.

ERNST GUSTAV HOFFMANN.

Witnesses:

ALLEN PARRY J ONES, FRED O. HARRIS. 

